Genetic variability of environmental sensitivity revealed by phenotypic variation in body weight and (its) correlations to physiological and behavioral traits.

Adaptive phenotypic plasticity is a key component of the ability of organisms to cope with changing environmental conditions. Fish have been shown to exhibit a substantial level of phenotypic plasticity in response to abiotic and biotic factors. In the present study, we investigate the link between environmental sensitivity assessed globally (revealed by phenotypic variation in body weight) and more targeted physiological and behavioral indicators that are generally used to assess the sensitivity of a fish to environmental stressors.

Pre-slaughter conditions, animal stress and welfare: current status and possible future research.

The present paper describes the main procedures used to slaughter fowl, pigs, calves and adult cattle, sheep, and farmed fish, starting on the farm and ending with the death of the animal at the abattoir. It reviews the currently known causes of stress, indicated by behavioural and physiological measurements on the animal level, and by post-mortem muscle metabolism. During the pre-slaughter period, psychological stress is due to changes of environment, social disturbances and handling, and physical stress is due to food deprivation, climatic conditions, fatigue, and sometimes pain.

Plasma cortisol response to stress in juvenile rainbow trout is influenced by their life history during early development and by egg cortisol content.

In this study, the consequences of the exposure of rainbow trout (Oncorhynchus mykiss) to a brief stress during early development were explored on the later response of fingerlings to stress. Firstly, we analyzed the ontogeny of cortisol production and that of the initial cortisol response to stress in developing fish. It is only at the eyed stage that the embryos started to produce some basal cortisol.

Exploration of the hypothalamic-pituitary-adrenal function as a tool to evaluate animal welfare.

Measuring HPA axis activity is the standard approach to the study of stress and welfare in farm animals. Although the reference technique is the use of blood plasma to measure glucocorticoid hormones (cortisol or corticosterone), several alternative methods such as the measurement of corticosteroids in saliva, urine or faeces have been developed to overcome the stress induced by blood sampling itself. In chronic stress situations, as is frequently the case in studies about farm animal welfare, hormonal secretions are usually unchanged but dynamic testing allows the demonstration of functional changes at several levels of the system, including the sensitization of the adrenal cortex to ACTH and the resistance of the axis to feedback inhibition by corticosteroids (dexamethasone suppression test).

Relationship between changes in mRNAs of the genes encoding steroidogenic acute regulatory protein and P450 cholesterol side chain cleavage in head kidney and plasma levels of cortisol in response to different kinds of acute stress in the rainbow trout (Oncorhynchus mykiss).

In this study, the expression of several genes involved in cortisol synthesis in head kidneys, the site of cortisol production, and in the rainbow trout (Oncorhynchus mykiss) was examined in response to two different acute stressors and an acute ACTH treatment. mRNAs levels of the "steroidogenic acute regulatory" (StAR) sterol transport protein, which transports cholesterol to the inner mitochondrial membrane as well as cytochrome P450 cholesterol side chain cleavage (P450(SCC)) were determined in head kidney (containing the interrenal tissue). In one experiment, we also quantified 3-beta-hydroxysteroid dehydrogenase (3B-HSD) and cytochrome P450(11beta) (11B-H) mRNAs.

Biochemical and behavioral effects of carbofuran in goldfish (Carassius auratus).

The effects of concentration (5, 50, and 500 microg/L) and duration (24, 48 h) of exposure to carbofuran, a carbamate insecticide, were assessed on brain catecholamine (norepinephrine [NE] and dopamine), plasma glucose, and hepatic glycogen contents and behavioral activities of goldfish (Carassius auratus). After 24 h of exposure to 50 and 500 microg/L, the level of NE was increased in the olfactory bulbs. The same effect was observed after a 48-h exposure to 500 and 50 microg/L in the telencephalic hemispheres and in the hypothalamus, respectively.

Isolation and characterization of novel glycoproteins from fish epidermal mucus: correlation between their pore-forming properties and their antibacterial activities.

In fish, a layer of mucus covers the external body surface contributing therefore, among other important biological functions, to the defense system of fish. The prevention of colonization by aquatic parasites, bacteria and fungi is mediated both by immune system compounds (IgM, lysozyme, etc.) and by antibacterial peptides and polypeptides.

Effect of confinement stress on circulating levels of growth hormone and two prolactins in freshwater-adapted tilapia (Oreochromis niloticus).

The aim of the present study was to assess a potential link between confinement stress and prolactin (PRL), the hormone responsible for adaptation to a hypoosmotic environment in freshwater-adapted tilapia (Oreochromis niloticus). The effect of stress on plasma levels of the two tilapia PRL forms, tiPRLI (or tiPRL188) and tiPRLII (or tiPRL177), was examined along with the effects on plasma levels of cortisol and growth hormone (GH). In a preliminary study, various sampling protocols (immediate sampling; sampling one by one; anesthesia at 0.

Interactions among Janus kinases and the prolactin (PRL) receptor in the regulation of a PRL response element.

PRL regulates milk gene expression, at least in part, by activating JAK2 kinase and STAT5 (signal transducer and activator of transcription 5), initially termed mammary gland factor (MGF). These experiments were initiated to gain a better understanding of the mechanisms of transcriptional activation via PRL receptor (PRL-R) signaling. Binding of PRL to the recombinant pigeon PRL-R-activated transcription driven by a 2.

Regulation of gill prolactin receptors in tilapia (Oreochromis niloticus) after a change in salinity or hypophysectomy.

Prolactin (PRL) receptors in gill tissue have been analyzed in tilapia (Oreochromis niloticus) after transfer from fresh water (FW) to brackish water (BW). This study has indicated the presence of only one class of tilapia PRL (tiPRL) receptor whatever the salinity. After transfer, however, the percentage of specific binding of the two forms of tiPRL (tiPRLI and tiPRLII) increased significantly.

Apical structures of "mitochondria-rich" alpha and beta cells in euryhaline fish gill: their behaviour in various living conditions.

Background: One of the characteristic features of the two types (alpha and beta) of "mitochondria-rich" (chloride) cells in the gill epithelium of freshwater fishes is the presence in their apical region of tubulovesicular structures. A further analysis of the ultrastructural features of these apical elements as well as that of their modifications under various living conditions should help to understand better the respective rôle of both alpha and beta cells in these conditions.

Methods: Atlantic salmon (Salmo salar) maintained in fresh water as well as tilapia (Oreochromis niloticus) maintained either in fresh water or in deionized water or in 20% saltwater were examined.

Absence of a tiGH effect on adaptability to brackish water in tilapia (Oreochromis niloticus).

The aim of this study was to investigate the possible role of growth hormone in the adaptation of tilapia (Oreochromis niloticus) to brackish water and to analyze its interactions with prolactin in this process. Plasma levels of growth hormone do not change upon transfer to brackish water. Treatment of intact tilapia in fresh water with growth hormone prior to transfer did not enable the fish to preadapt to brackish water: the duration of the hydromineral imbalance after transfer was the same in treated animals and controls.

Characterization of a single prolactin (PRL) receptor in tilapia (Oreochromis niloticus) which binds both PRLI and PRLII.

In tilapia, there are two forms of prolactin (PRL) whose effects on sodium and chloride movements differ and depend on the living environment of the fish. To see whether different receptors or the same receptor mediates these different effects, we have characterized the specific binding of both forms of tilapia (ti)PRL in two osmoregulatory organs, the gill and kidney. Two recombinant tiPRLs were used for this analysis.

Evidence that two tilapia (Oreochromis niloticus) prolactins have different osmoregulatory functions during adaptation to a hyperosmotic environment.

Two forms of prolactin (tiPRLI and tiPRLII), with only 69% sequence identity, have been previously described in the cichlid fish tilapia (Oreochromis species). In the present study we have attempted to investigate the biological activity of these two prolactin forms during adaptation to a hyperosmotic environment. For this purpose, we have developed two highly sensitive (sensitivity: 0.

Effects of prolactin on alpha and beta chloride cells in the gill epithelium of the saltwater adapted tilapia "Oreochromis niloticus".

Tilapia (Oreochromis niloticus), 21 g average body weight, were divided into two groups. A group was maintained in fresh water, whereas another group was adapted for 2 weeks to 20% salt water. Among the latter, fishes were injected every 2 days for a week with tilapia prolactin (ti-PRL I).

Production and purification of biologically active recombinant tilapia (Oreochromis niloticus) prolactins.

Recombinant expression vectors carrying tilapia prolactin-I or -II (tiPRL-I or tiPRL-II) cDNA were constructed and the tiPRL-I and II proteins were produced in E. coli as inclusion bodies. These inclusion bodies were dissolved in 6 mol urea/l.